U.S. patent application number 14/552213 was filed with the patent office on 2015-03-19 for post tensioned foundations, apparatus and associated methods.
The applicant listed for this patent is Darin R. Kruse. Invention is credited to Darin R. Kruse.
Application Number | 20150078837 14/552213 |
Document ID | / |
Family ID | 47743975 |
Filed Date | 2015-03-19 |
United States Patent
Application |
20150078837 |
Kind Code |
A1 |
Kruse; Darin R. |
March 19, 2015 |
POST TENSIONED FOUNDATIONS, APPARATUS AND ASSOCIATED METHODS
Abstract
Described herein are shallow post tensioned foundation systems
for mounting light to medium weight structures. Methods of
installation are also described. The systems, apparatus and methods
described can reduce waste, increase efficiency and reduce cost and
installation/construction time.
Inventors: |
Kruse; Darin R.; (Simi
Valley, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kruse; Darin R. |
Simi Valley |
CA |
US |
|
|
Family ID: |
47743975 |
Appl. No.: |
14/552213 |
Filed: |
November 24, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13592223 |
Aug 22, 2012 |
8920077 |
|
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14552213 |
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61526192 |
Aug 22, 2011 |
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Current U.S.
Class: |
405/232 ;
405/271 |
Current CPC
Class: |
E02D 27/28 20130101;
E02D 27/50 20130101; E02D 13/10 20130101; E02D 27/32 20130101; E02D
27/26 20130101 |
Class at
Publication: |
405/232 ;
405/271 |
International
Class: |
E02D 27/26 20060101
E02D027/26; E02D 27/32 20060101 E02D027/32; E02D 27/50 20060101
E02D027/50; E02D 27/28 20060101 E02D027/28 |
Claims
1. A method of installing a post tensioned foundation comprising
the steps: a. filling a feed cavity associated with a post
tensioned foundation installation device driven and rotated to a
depth with at least one type of aggregate; b. leaving a bottom
reaction plate attached to a tensioning rod at the depth; c. moving
the post tensioned foundation installation device upward to a
predetermined height thereby creating a void and releasing the at
least one type of aggregate into the void while rotating the post
tensioned foundation installation device until a specified amount
of aggregate is deposited around a perimeter of a mandrel; d.
compacting the at least one type of aggregate within the void
thereby creating compacted aggregate; e. securing a top reaction
plate to the tensioning rod over the compacted aggregate; and f.
installing the post tensioned foundation.
2. The method according to claim 1, wherein the post tensioned
foundation installation device is rotated.
3. The method according to claim 1, wherein steps c-d are repeated
until a desired amount of compacted aggregate has been
processed.
4. The method according to claim 1, wherein the post tensioned
foundation installation device comprises a first end and a second
end, the first end having a compaction element and the second end
having a power tool attachment section; a transversal rod guide
conduit originating at the compaction element and terminating at or
before the power tool attachment section; and an outer skin
defining an aggregate feed cavity, wherein the outer skin includes
at least one aggregate port.
5. The method according to claim 4, wherein a tension rod is housed
within the transversal rod guide and a bottom reaction plate rests
against the compaction element.
6. The method according to claim 1, further comprising filling the
remaining void with at least one type of soil and compacting the at
least one type of soil before step e.
7. The method according to claim 1, wherein steps c and d are
preformed simultaneously.
8. The method according to claim 1, wherein the top reactionplate
is precast concrete, steel, GFRP, plastic, nylon, HDPE, recycled
materials, or a combination thereof.
9. A post tensioned foundation installation system comprising a
mandrel including a first end and a second end, the first end
including a compaction element and the second end including a power
tool attachment section; a transversal rod guide conduit
originating at the compaction element and terminating at or before
the power tool attachment section; and an outer skin defining an
aggregate feed cavity, wherein the outer skin includes at least one
aggregate port.
10. The post tensioned foundation installation system according to
claim 9, wherein the aggregate feed cavity includes at least one
horizontal compaction element.
11. The post tensioned foundation installation system according to
claim 9, further comprising a tension rod assembly having a
tensioning rod and at least one reaction plate.
12. The post tensioned foundation installation system according to
claim 11, wherein the tensioning rod is housed within the
transversal rod guide and a bottom reaction plate rests against the
compaction element.
13. The post tensioned foundation installation system according to
claim 12, wherein the reaction plates are flat.
14. The post tensioned foundation installation system according to
claim 12, wherein at least one of the reaction plates is
conical.
15. The post tensioned foundation installation system according to
claim 14, wherein a bottom reaction plate is threaded.
16. The post tensioned foundation installation system according to
claim 11, wherein the tensioning rod is threaded.
17. The post tensioned foundation installation system according to
claim 11, wherein the compaction element includes at least one
first torque transfer element.
18. The post tensioned foundation installation system according to
claim 17, wherein at least one of the reaction plates includes a
second torque transfer element that weds with the at least one
first torque transfer element.
19. A post tensioned foundation installation system comprising a
mandrel including an outer skin having a first end and second end,
the first end including a first portion to attach a compaction
element and the second end including a second portion to attach a
drive adapter; a transversal rod guide originating at the first
end, extending through the mandrel, and held in place by at least
one transversal rod guide support; at least one interior compaction
element attached to the transversal rod guide and the outer skin to
assist in compacting aggregate against the side wall of a column
associated with at least one side aggregate port in the outer skin;
and a tensioning rod and at least one reaction plate.
20. The post tensioned foundation installation system according to
claim 19, wherein the at least one interior compaction element is
curved downward in a spiral.
21. The post tensioned foundation installation system according to
claim 19, wherein the tensioning rod is threaded.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a divisional application of U.S.
patent application Ser. No. 13/592,223 filed Aug. 22, 2012, which
claims the benefit under 35 U.S.C. .sctn.119(e) to U.S. Provisional
Application Ser. No. 61/526,192 filed Aug. 22, 2011, the entire
disclosures each of which are hereby incorporated by reference in
their entirety.
FIELD
[0002] Described herein are post tensioned foundations that can be
used in a variety of soil conditions. Apparatus and associated
methods of installing the foundations are provided.
BACKGROUND
[0003] A goal in construction can be to reduce costs, labor
requirements, material complexity and the like while attaining an
improved final product. Further, in light of growing environmental
concerns, construction methods that reduce global impact and are
sustainable have become as important as, if not more important,
than reducing costs.
[0004] Currently, most shallow foundations utilize designs
requiring manufactured materials, such as concrete and steel, that
are expensive, and in the case of steel piers, not immediately
available to the job site. Both the foundation design and
construction process can be costly and cumbersome due to a myriad
of factors such as material and transportation costs, soil
preparation, excavation, disposal costs, and time constraints
stemming from specifications, manufacturing, and delivery impacts
required for needed materials.
[0005] Also, in many cases, the soil beneath and around the current
shallow foundation systems require conditioning and/or
densification prior to construction. This ground improvement
procedure can be very costly and time consuming. In cases where
concrete foundations are specified, the existing soil must be
excavated and disposed of prior to concrete placement.
Additionally, once decommissioned, current shallow foundation
systems require excavation, disassembly, disposal, and
decommissioned site soil replacement and/or re-vegetation which may
have a negative effect on the environment.
[0006] As such, there is a need in the construction art for shallow
foundations that are cheaper than present methods, use readily
available materials, and reduce the environmental impact of the
construction project both during and after decommission and
removal.
SUMMARY
[0007] Generally described herein are post tensioned foundation
systems, methods of installing them, and apparatus used to install
them. The post tensioned foundations described can be useful for
anchoring light to medium weight structures and are cost effective,
save time and/or are sustainable.
[0008] Also described are post tensioned foundation installation
systems comprising:
[0009] a mandrel including a first end and a second end, the first
end including a compaction element and the second end including a
power tool attachment section; a transversal rod guide conduit
originating at the compaction element and terminating at or before
the power tool attachment point; and an outer skin defining an
aggregate feed cavity, wherein the outer skin includes at least one
aggregate port.
[0010] Post tensioned foundation installation systems can include a
casing having a hollow body with an interior diameter, a first end
and a second end including at least one aggregate feed port; a
mandrel comprising a gravel chute, a compaction element or striking
sledge, a force transfer foot, and an outer diameter that fits
within the interior diameter of the casing; and a transversal rod
guide conduit at a reaction plate. The mandrel can also include a
power tool attachment point at its second end.
[0011] Further described are post tensioned foundation installation
devices comprising a mandrel including a casing or outer skin
having a first end and a second end, the first end including a
portion to attach a compaction element and the second end including
a portion to attach a drive adapter. The compaction element can be
attached to the first end with a male or female connection. Within
the mandrel can be a transversal rod guide originating at the first
end, extending through the mandrel, and held in place by at least
one transversal rod guide support. Casing can include an aggregate
feed cavity and at least one aggregate port therein to allow
delivery of aggregate out the sides of the mandrel. The mandrel can
further include an elongated body portion located within the
casing. In some embodiments, the casing can be removed from the
mandrel.
[0012] A post tensioned foundation installation device or system
can further include a tension rod assembly having a tensioning rod
and a reaction plate. In other embodiments, the tension rod can be
housed within the transversal rod guide and the bottom reaction
plate can rest against the compaction element. In some embodiments,
a reaction plate can be flat or conical, and threaded or not
threaded. In some embodiments, the tensioning rod is threaded, and
in others it is not.
[0013] In other embodiments, the compaction element can include at
least one torque transfer element (e.g., a pin) and the reaction
plate can have another torque transfer element (e.g., a pin recess)
that weds with the other joining element. The opposite can also be
true.
[0014] Also described herein are methods of installing post
tensioned foundations comprising the steps: a. filling a feed
cavity associated with the post tensioned foundation installation
device that is driven and rotated to a depth with at least one type
of aggregate; b. leaving a bottom reaction plate attached to a
tensioning rod at the depth; c. moving the post tensioned
foundation installation device upward to a predetermined height
thereby creating a void and releasing the at least one type of
aggregate into the void while rotating the post tensioned
foundation installation device until a specified amount of
aggregate is deposited around the perimeter of a mandrel or minimum
torque requirements are exceeded; d. compacting the at least one
type of aggregate within the void thereby creating compacted
aggregate; and e. securing a top plate to the tensioning rod over
the compacted aggregate.
[0015] In some embodiments, the post foundation installation device
can be rotated without being axially driven. In other words, the
post foundation installation device can be rotated in place.
[0016] In one embodiment, post tensioned foundation installation
devices are described comprising: a mandrel with an elongated body
having a first end and a second end, the first end including a
compaction element and the second end including a power tool
attachment section. The elongated body can include a transversal
rod guide conduit originating at the compaction element and
terminating at or before the power tool attachment point. Also, an
outer skin or casing can surround at least a portion of the
elongated body portion or can form the elongated body portion and
can define an aggregate feed cavity, wherein the aggregate feed
cavity comprises at least one opening at the compaction element.
Also, one or more aggregate feed port can be located on or in outer
skin or casing.
[0017] In other embodiments, the tension rod assembly can be housed
within the transverse rod guide and the reaction plate can rest
against the compaction element.
[0018] In some embodiments, the methods further comprise filling
any remaining void with at least one type of soil and compacting
said at least one type of soil before the placing step. In another
embodiment, the securing step uses a nut threaded on the tensioning
rod. In still another embodiment, steps c and d are preformed
simultaneously. In other embodiments, the top reaction plate is
formed of precast concrete, GFRP, plastic, recycled materials,
nylon, metal, composites, polymers, or any strong,
non-compressible, and semi-ductile composite material known in the
art.
[0019] Also described herein are post tensioned foundations
comprising a power driven and rotated reaction plate anchored to a
tensioning rod buried within the earth; a column of compacted
aggregate on top of the power driven reaction plate; compacted
conditioned soil on top of the column of compacted aggregate; a top
plate on top of the compacted conditioned soil; and an anchoring
nut associated with the tensioning rod and on top of the top plate.
The post foundation systems can further comprise a belled compacted
aggregate segment at the bottom of the post foundation. Further
still, the post foundation systems can further comprise at least
one additional belled portion of compacted aggregate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1A illustrates a general post tensioned foundation
according to the present description. FIG. 1B illustrates another
general post tensioned foundation according to the present
description.
[0021] FIG. 2 illustrates an example rod and flat reaction plate
assembly.
[0022] FIGS. 3A and 3B illustrate an example rod and conical
reaction plate assembly.
[0023] FIGS. 4A-O illustrate an example mandrel. FIG. 4A is a
perspective view.
[0024] FIG. 4B is a perspective view with a portion of outer skin
removed. FIG. 4C is a cross-section. FIG. 4D is a side view of the
mandrel with the outer skin removed. FIG. 4E is a cross-section of
the mandrel without the outer skin. FIG. 4F illustrates an example
force transfer apparatus. FIG. 4G illustrates an outer skin. FIG.
4H illustrates a perspective view of a compaction element. FIG. 4I
is a top view of the top portion of the compaction element of FIG.
4H. FIG. 4J is a bottom view of the top portion of the compaction
element of FIG. 4H. FIG. 4K is a cross-section of the compaction
element of FIG. 4H. FIG. 4L is a top view of the bottom portion of
the compaction element of FIG. 4H. FIG. 4M is a bottom view of the
bottom portion of the compaction element of FIG. 4H. FIG. 4N is a
top view of an alternate bottom portion of the compaction element
of FIG. 4H. FIG. 4O is a bottom view of an alternate bottom portion
of the compaction element of FIG. 4H.
[0025] FIGS. 5A-O illustrate an example mandrel. FIG. 5A is a
perspective view. FIG. 5B is an exploded perspective view. FIG. 5C
is a side view. FIG. 5D is a top view and 5E is a bottom view.
FIGS. 5F-N illustrate various cross-sectional views. FIG. 5O is a
bottom perspective view of a casing.
[0026] FIGS. 6A-H illustrate another exemplary mandrel. FIG. 6A is
a partially exploded side view of the mandrel. FIG. 6B is a cross
section of the mandrel in FIG. 6A. FIGS. 6C-H are cross-sectional
and different direct views of the mandrel of FIG. 6A as outlined in
FIG. 6B.
[0027] FIGS. 7A-I illustrate an exemplary foundation installation
method according to the present description.
[0028] FIGS. 8A-M illustrate another exemplary temporary cased
foundation installation method according to the present description
using another mandrel device.
DETAILED DESCRIPTION
[0029] Described herein generally are post tensioned foundations
which can support light weight structures in a variety of soil
conditions. Apparatus and methods of installing the post tensioned
foundation are also described.
[0030] The post tensioned foundations can be referred to as post
tensioned shallow gravel columns (PTSGC) or light load (L.sup.2)
foundations and can be foundation systems generally designed to
support light to medium weight structures. The foundations can
consist of a reaction plate and rod assembly, at least one type of
compacted aggregate, and a surface mounted tensioning and lateral
resisting plate. When these elements are combined and pre-stressed,
a monolithic foundation system is created able to resist pullout,
compressive and lateral forces.
[0031] The foundations described herein can be used to support
light to medium loads such as solar panels, solar panel support
apparatus, street lights, playground equipment, telephone/electric
poles, street signs, fence posts, flag poles, and the like.
[0032] The foundations can be installed using a tool called a
mandrel that has been designed to drive and/or rotate the reaction
plate and rod assembly into the ground, fill the void with
aggregate during mandrel extraction, and then compact the newly
placed aggregate column thereby expanding the aggregate into the
surrounding soil. The mandrels described herein can be used with or
without a separate sleeve or casing.
[0033] Most current shallow foundation designs use concrete
footings or some other type of earth embedded high strength pier to
anchor and support above ground structures. Under some conditions
which include wind and seismic loading, the structural requirements
of a foundation system must be engineered to resist compressive,
tensile, and lateral loads. These multiple requirements place large
structural demands on current foundation elements which in most
cases are satisfied by the predominant use of concrete and steel in
the design. These materials are characterized as: dense (having
large mass to volume ratio), stiff (ability to resist high applied
force with little deformation), strong (having an ability to
withstand an applied stress without failure), costly to produce,
transport, and usually require removal at the end of their
lifecycle.
[0034] Foundation methods generally rely on the soil's bearing
capacity and/or friction to obtain their resistive capacity, yet
they must be designed to not exceed the soils strength or bearing
capacity. This relationship/interaction between the structure's
foundation (spread footing or pier) and the soil can lead to very
costly foundation designs due to the fact that the foundation
materials must scale up in size and strength to compensate for the
soil's inability to resist loads. For example, weaker soils require
larger and stronger foundation elements to "spread out" the loads
over a larger soil bearing area. All of the above requirements
result in generally expensive and sometimes cost prohibitive
foundations.
[0035] In contrast, the post tensioned foundations of the present
description can be simplified and structurally efficient designs
that incorporate readily available, light, and inexpensive
materials which can be assembled using installation processes,
tooling, and equipment yielding significant benefits when compared
to existing engineering and construction practice. Cost, schedule,
and environmental advantages are the result of a combination of
design technique, material selection, and installation equipment,
tooling, and processes. The effective use of the foundation's
structural elements combined with the installation method can
result in superior soil-structure interaction producing a more
efficient foundation system when compared to current foundation
systems.
[0036] The presently described pier foundation can be effectively
and efficiently installed in many different types of existing soils
and does not require the in situ soil to be improved or excavated
prior to the installation of the foundation systems. Thus, the
present foundations, systems, methods and apparatus can provide a
reduced price, increased construction speed, and/or environmental
advantage compared to current foundation systems. The construction
methods of the present foundations and systems simultaneously
densify the surrounding soil, improving the structural capacity of
the pier itself, at the same time that the pier construction is
occurring. This concurrent combination of ground improvement and
pier construction can yield high design and/or construction
efficiencies. Finally, once a site is decommissioned, the
foundation's design and construction materials facilitate site
dismantling with virtually no impact to the environment, making it
a sustainable technology.
[0037] As illustrated in FIG. 1, post tensioned foundation system
100 generally includes a reaction plate 102 anchored to tensioning
rod 104. Reaction plate 102 and tensioning rod 104 can be installed
into the earth by driving, rotation or both. A column of aggregate
106 is compacted on top of reaction plate 102. Optionally, atop
aggregate 106 is conditioned soil 108 compacted thereon. Tensioning
rod 104 has first end 110 anchored to reaction plate 102 and second
end 112 sticking out beyond ground level 114. Top plate 116 is
rested on top of the column (now compacted) and anchoring device
118 is used to hold top plate 116 in place thereby preserving the
tension within post tensioned foundation system 100. In some
embodiments, the system does not include conditioned soil 108.
Rather, column of aggregate 106 can extend from reaction plate 102
to top plate 116.
[0038] In other embodiments, the overall shape of the foundation
may vary. For example, some foundations can have a bell shape at
the bottom while others might not. Also, some may have bulges along
the body or top and others might not.
[0039] In an alternate embodiment, top plate 116 is placed directly
on top of aggregate 106. In some embodiments, as illustrated in
FIG. 1, the top of conditioned soil 108 is below ground level 114.
Yet in other embodiments, the top of conditioned soil 108 is at
about ground level 114. Top plate 116 can be formed of any strong,
non-compressible, and/or semi-ductile composite material. Example
material used to form top plate 116 can be precast concrete, steel,
GFRP, plastic, nylon, HDPE, recycled materials, or a combination
thereof. The material used can be dependent on cost, strength,
corrosion, weight, sustainability, and/or service life.
[0040] Reaction plate 102 can have a flat shape as illustrated.
However, in some embodiments, a reaction plate can have a conical
shape 120 or any other shape that can be used to achieve a
foundation as described.
[0041] In one embodiment, the systems described herein can be
designed to transfer tension, compression, and lateral loads from
an above ground structure directly to the in situ soil. The pier is
built with top and bottom reaction plates, a rod that connects the
plates together, and at least one compacted aggregate in between
the two plates that transfers loads to the soil. In order to bind
the soil-gravel matrix together, compressive (normal) force created
by pre-stressing the top and bottom plates sandwich the aggregate
between the top and bottom reaction plates as they are cinched
together using the tensioning rod and bolts. The above ground
compressive loads are transferred from the above ground structural
elements to the in situ soil through the rod, top reaction plate,
and the gravel with some of the load transferring down the rod to
the bottom reaction plate and compacted aggregate pier tip. Tensile
loads are transferred through the rod which is connected to the
bottom reaction plate. This entire assembly transfers its loads
through aggregate 106 and then to the surrounding soil via skin
friction. The tensile load can be resisted by the weight of the
column, the weight of the soil in failure wedge 122 outlined by
failure plane 124,124' as seen in FIG. 1, and/or soil shear
strength (cohesion and inter-particle friction).
[0042] The load capacity of the systems described herein can be
dependent on the density and strength of the surrounding soil and
the skin friction developed between the pier and the soil.
Therefore, a combination of aggregate materials and in situ soil
densification and compaction techniques improve the pier's
surrounding soil load bearing capacity, expand the pier's base
(belling), and simultaneously compact and densify the aggregate
column increasing the pier's load capacity. These efficiencies are
achieved using inexpensive structural and geotechnical materials.
The systems can further be constructed, for example, using a
"drifter" mounted on a 100 kW drill rig that provides both
rotational and compactive forces to densify the soil, install and
retract the mandrel, displace the gravel into the side wall and
densify the aggregate.
[0043] In one example embodiment, the surface area of the reaction
plate can vary from about 10 to about 150 square inches and be
comprised of a square, round, or hexagonal shape. The bottom of the
plate could be flat, rounded, or conically shaped. Reaction plates
according to the present description can be made of steel, plastic,
nylon, recycled materials, or any other strong and ductile
composite material known in the art.
[0044] The reaction plate's ground engaging surface can be smooth
or formed with a spiral configuration to facilitate insertion with
rotational force. The reaction plate's inner aggregate facing
surface can be smooth, or have specially designed torque transfer
elements used to transfer the rotational force supplied from a
mandrel to the reaction plate during installation. Torque transfer
elements can include pins or other protrusions as well as voids or
other features that can associate the pins, protrusion, or voids in
the joining element.
[0045] The reaction plate and rod assembly can be made of corrosive
or non-corrosive materials and could be joined by welding,
screwing, adhesive, compression, or a combination of some or all of
the above. The rod can be threaded or smooth, made of steel, glass
fiber reinforced polymer (GFRP), or other high tensile strength
materials.
[0046] For example, in one embodiment, tension rod assembly 200 as
illustrated in FIG. 2 includes both reaction plate 202 and
tensioning rod 204. Reaction plate 202 is flat in shape and held in
place by nut 206. In this embodiment, tensioning rod is threaded
and as such, nut 206 is threaded into first end 208 of tensioning
rod 204. A top plate (not illustrated) is placed through tensioning
rod 204 and a nut (not illustrated) is threaded onto tensioning rod
204 near second end 210.
[0047] In an alternate embodiment, as illustrated in FIGS. 3A and
3B, tension rod assembly 300 includes both reaction plate 302 and
tensioning rod 304. Here reaction plate 302 is conical in shape and
includes threads 306 to aid in rotationally inserting the reaction
plate and compacting the column perimeter soil. Tensioning rod
assembly 300 can be rotated during installation in the direction of
threads 306 or against the direction of threads 306. When rotated
in the same direction as the threads, the threads help pull the
mandrel into the ground. When rotated in the opposite direction of
the threads, the threads displace soil away from the cone
permitting the crowd force to advance the tooling. Tensioning rod
304 can be threaded and reaction plate 302 can simply screw onto
tensioning rod 304 through a threaded mounting hole 308. Reaction
plate 302 can have one or more first type of torque transfer
element 310 on its flat face 312 to accommodate a second type of
torque transfer element from a mandrel. Like tension rod assembly
200, tensioning rod 304 accommodates a top plate (not illustrated)
at end 314 placed through tensioning rod 304 and a nut (not
illustrated) is threaded onto tensioning rod 304 to hold top plate
in place near second end 314.
[0048] At least one type of aggregate, soil and/or sand can be used
in the post tensioned foundations described herein. Aggregate can
be natural or recycled and can include a binder material consisting
of concrete, asphalt, polymer, or combination of one or all. Both
size and shape of an aggregate can play a role in a particular
foundation design. In one embodiment, the aggregate can have an
average diameter of about 1/16 in, 1/8 in, about 1/4 in, about 3/8
in, about 1/2 in, about 5/8 in, about 3/4 in, about 7/8 in, about 1
in, between about 1/16 in and about 1 inch, between about 1/2 in
and about 1 in, between about 1/16 in and about 1/2 in, or between
about 1/8 in and about 3/4 in. In a preferred embodiment, the
diameter is about 3/8 inch. In another embodiment, the aggregate
can be pea shaped or in other words smooth or can have a rugged
surface. An exemplary rugged surface aggregate is crushed gravel.
Soil and/or sand can include finely ground material having an
average diameter of about 1/16 mm, 1/8 mm, about 1/4 mm, about 3/8
mm, about 1/2 mm, about 5/8 mm, about 3/4 mm, about 7/8 mm, about 1
mm, about 1.5 mm, about 2 mm, between about 1/16 mm and about 2 mm,
between about 1/2 mm and about 1 mm, between about 1/16 mm and
about 1/2 mm, or between about 1/8 mm and about 3/4 mm.
[0049] The top plate, also referred to as the top tensioning and
lateral load resisting plate, can have various physical
characteristics depending on a foundation design. A plate's surface
area can vary from about 10 square inches to about 300 square
inches. The plate can have a square or round shape and can have a
flat, rounded, or conical cross section. The plate can be made of
precast concrete, but can also be made of steel, GFRP, plastic,
nylon, recycled materials, or any strong, non-compressible, and
semi-ductile composite material known in the art.
[0050] The tensioning and lateral load resisting plate can have a
smooth surface or rough surface with a high coefficient of friction
facing the soil in order to maximize lateral load transfer to the
soil and foundation thru soil interaction. The top plate can be
made of corrosive or non-corrosive materials and could be joined to
the tensioning rod by welding, bolting, screwing, adhesive,
compression, or a combination of some or all of the above. In one
preferred embodiment, the top plate is held to the tensioning rod
using a nut threaded onto the tensioning rod.
[0051] A tool used to drive the reaction plate, compact/densify in
situ soil, deliver the aggregate, compact the aggregate and
optionally compact conditioned soil is a mandrel. An exemplary
mandrel 400 is illustrated in FIGS. 4A-O. Mandrel 400 includes an
elongated body portion 402 having first end 404 and second end 406.
First end 404 includes a force transfer surface 438 and second end
406 includes a power tool attachment section 410 which can be male
or female. Compaction element 408 is attached to first end 404 with
a male or female connection and rests against force transfer
surface 438. Within elongated body portion is transversal rod guide
412 originating at compaction surface 408 and extending through the
elongated body 402. Elongated body portion 402 can include a
striking sledge portion 460. Mandrel 400 further includes an outer
skin 416 attached to elongated body portion 402 and surrounding at
least a portion of elongated body portion 402. In one embodiment,
outer skin 416 circumferentially surrounds all of elongated body
portion 402 and can extend from first end 418 adjacent to
compaction element 408 to second end 420 near power tool attachment
section 410 as illustrated. In some embodiments, first end 418 of
outer skin 416 can aid in compaction. In other embodiments, first
end 418 of outer skin 416 may not aid in compaction.
[0052] Outer skin 416 can be attached to elongated body portion 402
using at least one stiffener spacer 422. In some embodiments, two
or more stiffener spacers are located in tiers. For example,
mandrel 400 includes first tier 424 and second tier 426. Each tier
can have two or more stiffener spacers, preferably four. In other
embodiments, tiers can be spaced to evenly distribute a load. For
example, one tier can include three stiffener spacers and a second
tier positioned 120 degrees offset the first tier and half way down
the first tier can contain three stiffener spacers.
[0053] An aggregate feed cavity 428 is defined between elongated
body portion 402 and outer skin 416 wherein feed cavity 428
comprises at least one opening 430 at compaction element 408. The
size 432 of the at least one opening is dependent on the size,
surface consistency and the like of the aggregate used. Further,
size 432 can be adjusted, for example, to accommodate different
sized or shaped aggregate as needed for a particular soil type by
attaching a different compaction element 408 that has the
appropriate seized opening 430 for the aggregate size used to
construct the pier.
[0054] To use a mandrel to drive a reaction plate into the earth, a
tension rod assembly including a reaction plate attached to a
tensioning rod is inserted into transversal rod guide 412. When the
tensioning rod assembly is fully inserted into the transversal rod
guide 412, the reaction plate can rest against compaction element
408. Further, as discussed above, compaction element 408 can
include one or more torque pins or recesses for torque pins on the
reaction plate.
[0055] First end 418 includes at least one gravel or aggregate port
440. In some embodiments, first end 418 includes three aggregate
ports. Elongated body portion 402 fits within outer skin 416 and
includes aggregate feed cavity 428, cricket 434, curved compaction
element 436, force transfer surface 438, and compaction element
408.
[0056] As torque is applied to the mandrel, a normal force can be
generated at curved compaction element 436 that displaces aggregate
into the side wall of a column. The torque can increase as the
rotationally induced inter-particle friction creates additional
aggregate drag and increasing column wall soil densification as the
aggregate column diameter expands into the surrounding soil. Then,
once pre-stated minimum torque thresholds are exceeded, the casing
and mandrel are incrementally withdrawn to continue a belling
process at the next elevation. As the tool is raised, aggregate can
fill the created void below via aggregate port 430 which can then
be compacted using drill equipment's crowd and hammer forces. Such
a process will be explained in greater detail below.
[0057] Compaction Element 408 is comprised of first compaction foot
442 and second compaction foot 444. First compaction foot 442 can
have the aggregate chute 430 sloped in where it is closer to the
outside at the top of first compaction foot 442 and closer to the
inside (or rod guide conduit) at the bottom. Other embodiments can
have an aggregate chute 430 that goes straight through the first
compaction foot 442. Second compaction foot 444 can have a tapered
outside perimeter 446 with angle 448 from the horizontal to
increase the soil compaction against the side wall of the column.
The aggregate chute 430, at the bottom of the second compaction
foot 444, can be tapered 452 away from the direction of rotation in
order to push the aggregate out without crushing it. Other
embodiments can be used for the second compaction foot depending on
the soil and aggregate type. For example, the second compaction
foot 450 can be comprised of an outer first ring 451 that can have
a flat or tapered outer perimeter 452. A smaller diameter void 430
is then formed by an interior circular "washer" element 454 formed
inside the middle of the first ring 451 creating a continuous round
chute 430 for dispensing aggregate.
[0058] In each embodiment, above, first compaction feet and second
compaction feet can be formed as a single piece or a separate
pieces that can be welded together or joined during assembly. In
one embodiment, a first compaction foot and a second compaction
foot can be shaped out of a single piece of metal (e.g., steel) by
an appropriate tool (e.g., milling tool).
[0059] Another installation system 500 is illustrated in FIGS.
5A-0. System 500 includes top surface 502 and bottom face 504.
Compaction generally occurs at and adjacent to bottom face 504.
Mandrel casing 506, as illustrated in FIG. 5O, surrounds striking
sledge 508. Casing 506 includes a generally cylindrical shape with
a hollow interior 510, a first side 512 and a second side 514.
Casing can have a thickness of about 1/8 inch, 1/4 inch, 1/2 inch
3/4 inch, or 1 inch.
[0060] Casing 506 can be attached to striking sledge 508 using at
least one stiffener spacer 530. In some embodiments, two or more
stiffener spacers are located in tiers. In other embodiments, tiers
can be spaced to evenly distribute a load. For example, one upper
tier can include three or four evenly spaced stiffener spacers and
a second tier offsetting the first tier and positioned below the
first tier can contain three or four stiffener spacers. Second side
514 includes at least one gravel or aggregate port 516. In some
embodiments, second side 514 includes three or four aggregate
ports. Striking sledge fits within hollow interior 510 and includes
stem coupling 518 (which can be male or female), aggregate chute
520, cricket 522, triangular compaction element 524, and axial
compaction element 526 which can be attached with a male or female
connection (not illustrated) including tension rod conduit 528.
[0061] As torque is applied to the mandrel, a normal force can be
generated at the compaction element 524 that displaces aggregate
into the side wall of a column. The torque can increase as the
rotationally induced inter-particle friction creates additional
aggregate drag and increasing column wall soil densification as the
aggregate column diameter expands into the surrounding soil. Then,
the casing and mandrel are incrementally withdrawn to continue pier
wall densification at the next elevation. As the tool is raised,
aggregate can fill the created void below via aggregate chute 520
which can then be compacted using drill equipment's crowd and
hammer forces.
[0062] Another exemplary mandrel 600 is illustrated in FIGS. 6A-H.
Mandrel 600 includes a casing 614 having a first end 602 and second
end 604. First end 602 can include a portion to attach compaction
element 606 and second end 604 can include a portion to attach
drive adapter 616. Drive adapter 616 can include power tool
attachment section 608 which can be male or female. Compaction
element 606 is attached to first end 602 with a male or female
connection and can rest against it. Within mandrel 600 is
transversal rod guide 610 originating at first end 602, extending
through the mandrel 600, and held in place by at least one
transversal rod guide support 612. Mandrel 600 further includes an
outer skin or casing 614. In one embodiment, casing 614
circumferentially surrounds all of transversal rod guide 610 and
can extend from first end 602 adjacent to compaction element 606 to
second end 604 near power tool attachment section 608 as
illustrated. In some embodiments, first end 602 can aid in
compaction by transferring force from drive adapter 616 located at
second end 604 to compaction element 606.
[0063] Casing 614 as described can be attached to transversal rod
guide 610 using at least one transversal rod guide support 612. In
some embodiments, two or more transversal rod guide supports are
located in tiers.
[0064] An annulus aggregate cavity 618 is defined between
transversal rod guide 610 and casing 614 wherein annulus aggregate
cavity 618 includes at least one port 620 at compaction element
606. The size of the at least one port is dependent on the size,
surface consistency and the like of the aggregate used. Further,
the size can be adjusted, for example, to accommodate different
sized or shaped aggregate as needed for a particular soil type by
attaching a different compaction element 606 that has the
appropriate seized port 620 for the aggregate size used to
construct the pier.
[0065] To use mandrel 600 to drive a reaction plate into the earth,
a tension rod assembly including conical reaction plate 622 with
threaded mounting hole 308 permits screwed attachment to tensioning
rod 304 which is then inserted into transversal rod guide 610. When
the tensioning rod assembly is fully inserted into the transversal
rod guide 610, the interior 628 of conical reaction plate 622 can
rest against the exterior 632 of compaction element 606. The
driving or axial force of the mandrel 600 can be transferred from
the compaction element 606 face 636 to the conical reaction plate
622 drive surface 627. Further, conical reaction plate 622 can
include one or more wings 624 formed from cuts 630 in the plate.
The wings 624 can allow the upper diameter 626 to expand as
aggregate and compaction element 606 are driven into interior 628
of conical reaction plate 622 thereby deforming the wings. Deformed
wings can provide increased resisting force preventing tensile
extraction of tensioning rod assembly 200 or 300 once
installed.
[0066] Compaction Element 606 can have aggregate port 620 on sloped
face 632. Also, compaction element 606 can have port 634 on face
636 to allow tensioning rod 304 traverse it. Compaction element 606
can further be threaded onto casing 614. Compaction element 606 can
have any shape that allows aggregate compaction and aggregate feed
there through.
[0067] Further, in order to retain aggregate within annulus
aggregate cavity 618 until release is needed through aggregate port
620, conical reaction plate 622 can include one or more torque
transfer elements 638 that can match the opening shape of aggregate
port 620. Torque transfer elements 638 can prevent premature
aggregate release when conical reaction plate 622 is fitted against
compaction element 606.
[0068] Mandrel 600 can further include at least one interior
compaction element. An interior compaction element can be attached
to transversal rod guide 610 and casing 614. The interior
compaction elements 642 and/or 644 can assist in compacting
aggregate against the side wall of a column as aggregate is pushed
out during mandrel rotation of at least one side aggregate port 640
in casing 614. Also, interior compaction elements can prevent
aggregate from traveling back up annulus aggregate cavity 618
during compaction. Interior compaction elements can be curved to
further aid in torque induced lateral aggregate compaction and
prevention of aggregate reverse flow back up into the mandrel
during axial compaction. Such a curve can also be downward in a
spiral configuration. In one embodiment, mandrel 600 includes one,
two, three, four, five, six, seven, eight, nine, ten, eleven,
twelve, or more interior compaction elements which may or may not
be curved. Each interior compaction element can be matched up with
a side aggregate port 640 and/or be at a different elevation within
the mandrel. As such, casing can include one, two, three, four,
five, six, seven, eight, nine, ten, eleven, twelve, or more
aggregate ports in it. In another embodiment, mandrel includes at
least first curved compaction element 642 and second curved
compaction element 644.
[0069] As torque is applied to the mandrel, a normal force can be
generated at curved compaction elements that displace aggregate
into the side wall of a column. The torque can increase as the
rotationally induced inter-particle friction creates additional
aggregate drag and increasing column wall soil densification as the
aggregate column diameter expands into the surrounding soil. Then,
once pre-stated minimum torque thresholds are exceeded, the mandrel
can be incrementally withdrawn to continue the process at a next
elevation. As the tool is raised, aggregate can fill the created
void below via aggregate port 620 which can then be compacted using
drill equipment's crowd and hammer forces.
[0070] Aggregate can be fed into annulus aggregate cavity 618
through aggregate fill port 646 in casing 614. Aggregate fill port
646 can be located anywhere on mandrel 600 that allows proper
foundation installation while still allowing the cavity to be
filled with aggregate. In one embodiment, aggregate fill port 646
can be located near second end of mandrel 600. In another
embodiment, aggregate fill port 646 can be located in drive adapter
616.
[0071] Further described herein are methods of installing post
tensioned foundations and foundation systems. The methods generally
can be more cost effective, less labor intensive, faster, and/or
provide a better end product when anchoring light to medium weight
structures using the present foundations and foundation
systems.
[0072] The first step in constructing a post tensioned foundation
system as described can be to attach a mandrel as described herein
to a hydraulic hammer arm of a heavy construction vehicle. The
mandrel is positioned such that the power tool attachment section
engages the hydraulic hammer. The mandrel is secured to the hammer
using appropriate fixing methods known in the art. In other
embodiments, the mandrel can be equipped with a
connection/disconnection contraption such as a socketed male/female
threaded connection that attaches (e.g., quickly and/or easily) and
detaches from the hammer for interchanging of different sized
mandrels for different post tensioned foundation load needs or
differing soil types on a construction site.
[0073] A first example method of installing a foundation according
to the present description using a mandrel as described herein is
illustrated in FIGS. 7A-I. Referring to FIG. 7A, mandrel 702 is
fitted with a tensioning rod assembly including a tension rod 704
and reaction plate 706 as described herein. Mandrel 702 can include
a solid or ridged coupling device for temporarily mating with a
hydraulically powered drill head assembly commonly referred to as a
drifter, capable of providing both rotational 718 and compressive
736 forces to the tooling. The tension rod and reaction plate
assembly is loaded into the transverse rod guide 708 within the
mandrel 702. For this example, tension rod 704 is threaded and the
reaction plate 706 is conical in shape with threads. Reaction plate
706 further includes two torque transfer elements that wed with
torque transfer elements in the compaction element of the
mandrel.
[0074] Next, a location 710 in the earth where the post tensioned
foundation is to be installed is chosen. Generally, engineers and
architects have plotted strategic locations for the foundation, but
if they have not, locations can be chosen on site and appropriate
mandrel sizes can be used based on the soil conditions. Once
location 710 has been determined for a post tensioned foundation,
reaction plate 706 on top of mandrel's compaction surface 712 is
engaged with location 710 and the hammer is activated thereby
pounding reaction plate 706 into the earth. Mandrel 702 is attached
to a hammer arm of an appropriate machine.
[0075] Referring now to FIG. 7B, as mandrel 702 and hence reaction
plate 706 is driven farther into in situ soil 714, downward force
716 is used and can also be accompanied with rotational force 718.
However, rotational force 718 may not be needed in all cases.
Further, as the apparatus is driven further into in situ soil 714,
compacted soil 720 is created around the apparatus. This compacted
soil aids in improving the soil and aggregate column's stressed
state within the completed post tensioned foundation. When a
desired depth 722 is reached, the hammer is deactivated.
[0076] Next, as illustrated in FIG. 7C, at least one type of
aggregate 724 is fed into aggregate feed cavity 726 defined within
mandrel 702. The amount of aggregate 724 fed into aggregate feed
cavity 726 can be a predetermined amount consistent with the void
created by lifting the mandrel in the next step. The predetermined
amount of aggregate is calculated based on the volume of void by
lifting the mandrel a predetermined distance.
[0077] The tensioning rod assembly is then released from mandrel
702. In other embodiments, aggregate 724 can be loaded into the
aggregate feed cavity 726 before the tensioning rod assembly is
installed in the ground.
[0078] Mandrel 702 can then be lifted 728 a predetermined distance
730 as illustrated in FIG. 7D. As mandrel 702 is lifted, aggregate
724 from aggregate feed cavity 726 is dispensed through the annulus
at compaction surface 712 as gravity pulls it down into void 732,
thereby filling it with aggregate 724. The weight of the reaction
plate and rod assembly and the weight of aggregate 724 and friction
from compacted soil 720 can hold reaction plate 706 at desired
depth 722. Predetermined distance 730 may be dependent on such
factors as available compaction force, soil type, aggregate size,
aggregate shape, depth and/or volume of void, and the like.
[0079] Then, as illustrated in FIG. 7E, in addition to rotation,
the hammer is re-activated and aggregate 724 is compacted within
void 732 using downward force 736 thereby compacting the aggregate
and enhancing creation of the gravel bulb 738 whose normal force is
resisted by compacted soil 720. The re-activation of the hammer can
be deployed for a predetermined amount of time dependent on such
factors as soil type, applied hammer force, compaction surface 712
size and geometry, aggregate size, aggregate shape, depth and/or
volume of void, and the like.
[0080] In FIGS. 7F and 7G, the steps illustrated in FIGS. 7C, 7D
and 7E are repeated. In FIG. 7F, second load of aggregate 740 is
loaded into aggregate feed cavity 726. Then, mandrel 702 is raised,
again, a predetermined distance. As mandrel 702 is raised 742,
second load of aggregate 740 from aggregate feed cavity 726 is
dispensed through the aggregate ports at compaction surface 712 as
gravity pulls it down into void 744 illustrated in FIG. 7G, thereby
filling it with second load of aggregate 740 on top of the already
compacted aggregate 738 below.
[0081] Once second load of aggregate 740 has been fed into void
744, again, the hammer is re-activated and second load of aggregate
740 is compacted within void 744 using downward force 746 thereby
compacting second load of aggregate 740 on top of gravel bulb 738.
The steps illustrated in FIGS. 7F and 7G can be repeated as
necessary to reach a desired height 748 of compacted aggregate
illustrated in FIG. 7H.
[0082] As an optional next step illustrated in FIG. 7H, conditioned
soil 750 can be poured either directly into remaining void 752 or
can be fed through aggregate feed cavity 726. This conditioned soil
750 can then be compacted using mandrel 702, the hammer and
downward force 754.
[0083] Mandrel 702 can be a mandrel as described in FIGS. 4A-O,
FIGS. 5A-O, or 6A-H.
[0084] Referring to FIGS. 7H and 7I, top plate 756 can be placed
either on top of compacted, conditioned soil 750 or directly on top
of the compacted aggregate if the conditioned soil step is
optionally skipped. Top plate 756 can have a hole in its center to
accommodate tension rod 704 which may still extend out of the post
tensioned foundation. Then, because tension rod 704 is threaded, a
nut (or securing device if tension rod 704 is not threaded) is used
to hold top plate 756 in place atop the post tensioned foundation.
By bolting top plate 756 in place, the increased soil and aggregate
stressed state of the post tensioned foundation can be
preserved.
[0085] Another example system to install a foundation according to
the present description is illustrated in FIGS. 8A-M. The tools
used can be attached to common machinery. First, a location can be
chosen as described above. Tool 800 includes port 802, casing 804,
stem 806, displacement tool 810 and a mandrel 834. As illustrated
in FIG. 8A, tool 800, can be used perpendicular to soil 812 or at
varying angles 814 or 816. In some embodiments, each system
described herein can be used or installed at different angles to
accommodate terrain variations, load characteristics, above ground
structure requirements and the like. For example, angles of about
5.degree., 10.degree., 15.degree., 20.degree., 30.degree.,
40.degree., 50.degree., 60.degree., 70.degree. or more can be
utilized.
[0086] A conical shaped driving and displacement insertion tool can
simultaneously displace, drive and screw the temporary casing into
the ground displacing the soil to the outside of the pier resulting
in densified soil and increasing the soil stress.
[0087] Once a desired depth is achieved, the driving and
displacement insertion tool can be removed and the mandrel, bottom
reaction plate and rod assembly are inserted into the casing. Then,
the complete pier's supply of aggregate may be placed into the
outer casing thereby charging the mandrel with aggregate.
[0088] The compaction process begins as the mandrel is hammered
down into the aggregate previously placed at the toe of the pier
compacting the pier's base and advancing the mandrel's side ports
beyond the bottom of the stationary outer casing. Rotation of the
mandrel is then commenced, initiating the pier sidewall compaction
method accomplished through inter-particle friction created at the
interface of the rotating aggregate with the stationary soil. This
friction causes larger aggregate rock particles to decelerate. The
advancing/rotating triangular compaction element then can force the
aggregate out through the mandrel's horizontal ports into the
yielding soil-grinding the aggregate into the pier's sidewall,
expanding (or belling) the bottom of the pier. Once the pier's
sidewalls are expanded and densified with the aggregate-soil
composite, the mandrel and casing can be incrementally raised
permitting some of the stored aggregate to fall out of the
mandrel's force transfer foot bottom openings, filling the void
left by the mandrel's retreat. The freshly placed aggregate is then
engaged with the mandrel's force transfer foot and vectored
compaction including both horizontal (lateral) and vertical (axial)
aggregate compaction is achieved by application of axial compactive
hammer force.
[0089] The method can rely on a torque induced normal force that
pushes the gravel out of the discharge ports located on the side of
the rotating mandrel as the particles engage with the soil
surrounding the tool. As the aggregate layer builds up around the
perimeter of the discharge ports, friction increases creating
addition torque requirements on the system. Once specified torque
requirements are achieved, the tool is raised permitting aggregate
to exit through the base of the tool filling the void created by
tool extraction. The tool is then reengaged with the aggregate
(axial force) and compacted using the compaction mode. Axial force
is created by a hydraulically driven hammering action
(reciprocating piston) of a drifter.
[0090] The geotechnical stress state of the soil can be developed
during column construction as the aggregate is compacted into the
surrounding soil during simultaneous rotationally induced lateral
compaction and vectored lateral and axial compaction created during
the phased raising-filling-compaction process accomplished by the
combination of a drifter and mandrel acting on the soil and
aggregate matrix.
[0091] In addition to a particularly shaped mandrel foot used to
apply both normal and lateral compactive forces, the system can
rely on rotationally induced torque and inter-particle friction
created by the surrounding soil and aggregate interface to force
the aggregate laterally into the pier sidewalls thereby expanding
the pier's diameter at the base. This increase in pier diameter at
the base of the aggregate column increases the size of the failure
wedge increasing the capacity of the pier in tension.
[0092] Further to the above explanation, as a first step in using
tool 800 to install a pier as illustrated in FIG. 8B, temporary
casing 804 is driven into soil 812 at a predetermined angle (e.g.,
angle 814) using displacement tool 810. Here, the angle can be
90.degree. or perpendicular to soil 812. Using the applied forces
described above, the entire temporary casing 804 and tool 800 can
be rotated 818 as the tool is advanced into the soil. As advanced,
displacement tool 810 can create improved soil 820 or densified
soil. As described above, tool 800 can be advanced and optionally
rotated using an impact hammer attached to thread 822.
[0093] Once desired depth 824 has been reached as illustrated in
FIG. 8C, stem 806 and displacement tool 810 are removed from casing
804. Once stem 806 and displacement tool 810 are removed, as
illustrated in FIG. 8D, void 826 is created where the tip portion
of displacement tool 810 previously resided.
[0094] Then, as illustrated in FIG. 8E, aggregate 828 is added
through port 802 to fill about the entirety of void 826. Next, as
illustrated in FIG. 6F, tensioning rod 830 attached to reaction
plate 832 are fitted into mandrel 834 which is inserted into the
casing 804 and placed atop aggregate 828. Mandrel 834 can be sized
to fit within casing within about 1/16 inch, about 1/8 inch, about
1/4, in about 1/2 inch, about 3/4 inch, or about 1 inch. Again,
similar to FIG. 7G, additional aggregate can be added through port
802 to fill mandrel 834 and casing 804 up to port 802.
[0095] The load capacity of a pier system described herein can be
dependent on the density and strength of the surrounding soil, the
skin friction developed between the pier and the soil, and the
diameter of the pier. Therefore, a combination of aggregate
materials and in situ soil densification and compaction techniques
can improve the system's surrounding soil load bearing capacity,
expand the pier's base (belling), and simultaneously compact and
densify the aggregate column increasing the pier's load
capacity.
[0096] Mandrel 834 coupled with the sequence of construction steps
described herein can simultaneously push soil into the side wall of
a column and compact aggregate and soil using both rotational and
compactive (axial) forces. The piers can be constructed using:
non-corrosive, structurally efficient, light weight, structural and
geotechnical materials, specially designed and engineered drilling
tools and temporary casings, and a hydraulically powered "drifter"
mounted on a 100 kW tracked drill rig that can provide both
rotational 840 and compactive 848 forces to the tools that densify
the soil, install and retract the casing, and displace the gravel
into the pier's side wall while constructing the pier.
[0097] Mandrel 834 can be a mandrel as described in FIGS. 4A-O,
FIGS. 5A-O, or 6QA-H.
[0098] As torque is applied to the mandrel, a normal force can be
generated at a compaction element (e.g., compaction elements 436,
524, or 642) that displaces aggregate into the side wall of a
column. The torque increases as the rotationally induced
inter-particle friction creates additional aggregate drag and
increasing column wall soil densification as the aggregate column
diameter expands into the surrounding soil. Then, the casing and/or
mandrel are incrementally withdrawn to continue the belling process
at the next elevation. In one embodiment, the mandrel can be
incrementally withdrawn once pre-stated minimum torque thresholds
are exceeded. As the tool is raised, aggregate can fill the created
void below via aggregate port which can then be compacted using
drill equipment's crowd and hammer forces. Such a process will be
explained in greater detail below.
[0099] As illustrated in FIG. 8H, mandrel 834 is advanced using
drilling equipment supplied crowd and hammer axial compactive force
848 to consolidate aggregate 828 at pier tip 836. Once mandrel 834
has exposed its horizontal ports (e.g., horizontal ports 440, 516,
or 640) past the casing 804, optional rotation 840 of mandrel 834
commences in addition to the hammer force. As more axial 848 and
torque 840 induced forces are applied by mandrel 834 to the
aggregate, the pier tip 836 can become bulbous in shape.
[0100] Mandrel 834 and casing 804 can then be concurrently lifted
842 in increments as illustrated in FIG. 8I. These increments can
be about 2 inches, about 4 inches, about 6 inches, about 8 inches,
about 10 inches, about 12 inches, about 18 inches, about 24 inches,
about 30 inches, about 36 inches or more. Optional rotation 840 can
continue as mandrel 834 and casing 804 are lifted. Mandrel 834 is
then reengaged with the aggregate 828 newly delivered to the void
created as mandrel 834 and casing 804 are lifted. Subsequent lifts
of mandrel 834 and casing 804 can be commenced followed by
compaction and optional rotation forces. As is illustrated in FIG.
8J, second bulbous shape 844 can be created as both horizontal
force and vertical force are applied by mandrel 834.
[0101] As illustrated in FIG. 8K, once pier aggregate height
reaches ground level 846, compaction 848 of pier top is commenced.
Again vertical hammering and optionally rotation are provided by
mandrel 834. As mandrel 834 is advanced out of casing 804, a third
bulb 850 can be created near ground level 846. After compaction is
complete, as illustrated in FIG. 8L, mandrel 834 and casing 804 are
removed 852 leaving tensioning rod 830 emanating from the surface.
Tensioning rod 830 can optionally be threaded.
[0102] Second reaction plate 854, as illustrated in FIG. 8M, is
then placed atop newly formed pier and secured using securing
device 858. Second reaction plate can be similar or the same as
reaction plate reaction plate 832 or can be different. For example,
second reaction plate 854 can be a plate or large diameter washer
made of precast concrete, GFRP, plastic, recycled materials, nylon,
metal, composite, polymer, or any other strong, non-compressible,
and semi-ductile composite material known in the art and formed to
disperse the loads as long as the pier's column strength and the
soils stressed state remains intact. Securing device can be a nut
that is threaded on tensioning rod 830. In other embodiments,
securing device can be welded or glued to tensioning rod 830.
[0103] Optionally, the formation of a column as described herein
can be accomplished using a belling tool. In such an embodiment, a
separate belling tool is used to create a bell at the bottom of the
column and an axial compaction mandrel is used to compact the
aggregate and build the remainder of the column. The bell is a
bottom portion that can have a wider diameter than the rest of the
column. Once a casing and shoe assembly has been hammered and
rotated to an appropriate depth, a belling tool is inserted and
driven just below the shoe. The belling tool is opened using an
offset drive shaft and it is rotated around the circumference using
the drill stem. This process causes the soil to be pushed out
laterally, thus compacting the surrounding pier wall and creating a
bigger void. Next, the bell tool is removed and the void is filled
with gravel and compacted by the mandrel as described above.
[0104] The mandrels and, if used, temporary casings described
herein can be sized appropriately for a particular application. For
example, a foundation constructed in less dense organic material
such as peat, a larger diameter mandrel (and accompanying casing)
can be used to create a pier with equal bearing and tensile
strengths as as a smaller diameter pier constructed in more dense
material, wherein a smaller diameter mandrel and casing can be
used. Mandrel diameters in general range from about 3 inches to
about 10 inches, from about 4 inches to about 12 inches, from about
6 inches to about 18 inches, from about 18 inches to about 24
inches, from about 24 inches to about 30 inches or from about 30
inches to about 36 inches. In one embodiment, the diameter of the
mandrel is about 8 inches. The length of a mandrel can determine
the depth of a foundation. Lengths can range from about 12 inches
to about 18 inches, from about 18 inches to about 24 inches, from
about 24 inches to about 30 inches, from about 30 inches to about
36 inches, from about 36 inches to about 42 inches, from about 42
inches to about 48 inches, from about 48 inches to about 54 inches,
from about 54 inches to about 60 inches, from about 60 inches to
about 66 inches, from about 66 inches to about 72 inches, from
about 72 inches to about 78 inches, from about 78 inches to about
84 inches, from about 84 inches to about 90 inches, from about 90
inches to about 96 inches, from about 96 inches to about 102
inches, from about 102 inches to about 108 inches, or more.
[0105] In some embodiments, the foundation systems described can be
easily decommissioned and are environmentally sustainable. For
example, the post tension system or tensioning rod assembly
comprised of the plates (e.g., a top plate and a bottom plate) and
rod assembly are the only manmade products that might require
removal upon decommission. This simple task is in comparison to
large concrete foundations commonly used including imbedded rebar.
Also, the foundations described can be exhumed in a single step and
he materials recycled, disposed of, or even in some cases the
aggregate reused in re-compacting/filling the removed pier's
void.
[0106] Further, in some embodiments, the foundation systems can be
installed without the need for elaborate machinery or materials.
Such an arrangement can increase simplicity while reducing time and
cost of a project. Again, all that may be needed is aggregate sized
for a particular application, a reaction plate, a tensioning rod,
and a mandrel and, if used, a temporary casing and mandrel matched
pair. This simplicity is in contrast to common methods which
require complex machinery and delivery systems, large, non-reusable
parts for each foundation (e.g. corrosion protected steel piers or
reinforced concrete footings), material removal (e.g. exhumed soil
by an auger), material processing stations, lengthy set times (e.g.
with concrete), and the like.
[0107] The foundations described herein can be used to anchor light
to medium weight structures. From a plain weight standpoint, each
foundation can sustain a compressive weight load of about 100 lbs,
about 500 lbs, about 1,000 lbs, about 1,500 lbs, about 2,000 lbs,
about 2,500 lbs, about 3,000 lbs, about 3,500 lbs, about 4,000 lbs,
about 4,500 lbs, about 5,000 lbs, about 5,500 lbs, about 6,000 lbs,
about 6,500 lbs, about 7,000 lbs, about 7,500 lbs, about 8,000 lbs,
about 8,500 lbs, about 9,000 lbs, about 9,500 lbs about 10,000 lbs,
about 11,000, about 11,500, about 12,000, about 12,500, about
13,000, about 13,500, about 14,000, about 14,500, about 15,000,
about 15,500, about 16,000, about 16,500, about 17,000, about
17,500, about 18,000, about 18,500, about 19,000, about 19,500,
about 20,000, between about 10,000 lbs and about 20,000 lbs,
between about 5,000 lbs and about 15,000 lbs, between about 15,000
lbs and about 20,000 lbs, between about 100 lbs and about 20,000
lbs, between about 500 lbs and about 15,000 lbs, between about
10,000 lbs and about 15,000 lbs, at least about 100 lbs, at least
about 200 lbs, at least about 500 lbs, at least about 1,000 lbs, at
least about 5,000 lbs, or at least about 10,000 lbs. This weight
number can change depending on the size and shape of the mounted
structure(s). For example, wind can have a bearing on larger
surface area structures. A skilled artisan understands the
structural needs and can vary weight requirements with structure
size and shape.
[0108] Unless otherwise indicated, all numbers expressing
quantities of ingredients, properties such as molecular weight,
reaction conditions, and so forth used in the specification and
claims are to be understood as being modified in all instances by
the term "about." Accordingly, unless indicated to the contrary,
the numerical parameters set forth in the specification and
attached claims are approximations that may vary depending upon the
desired properties sought to be obtained by the present invention.
At the very least, and not as an attempt to limit the application
of the doctrine of equivalents to the scope of the claims, each
numerical parameter should at least be construed in light of the
number of reported significant digits and by applying ordinary
rounding techniques. Notwithstanding that the numerical ranges and
parameters setting forth the broad scope of the invention are
approximations, the numerical values set forth in the specific
examples are reported as precisely as possible. Any numerical
value, however, inherently contains certain errors necessarily
resulting from the standard deviation found in their respective
testing measurements.
[0109] The terms "a," "an," "the" and similar referents used in the
context of describing the invention (especially in the context of
the following claims) are to be construed to cover both the
singular and the plural, unless otherwise indicated herein or
clearly contradicted by context. Recitation of ranges of values
herein is merely intended to serve as a shorthand method of
referring individually to each separate value falling within the
range. Unless otherwise indicated herein, each individual value is
incorporated into the specification as if it were individually
recited herein. All methods described herein can be performed in
any suitable order unless otherwise indicated herein or otherwise
clearly contradicted by context. The use of any and all examples,
or exemplary language (e.g., "such as") provided herein is intended
merely to better illuminate the invention and does not pose a
limitation on the scope of the invention otherwise claimed. No
language in the specification should be construed as indicating any
non-claimed element essential to the practice of the invention.
[0110] Groupings of alternative elements or embodiments of the
invention disclosed herein are not to be construed as limitations.
Each group member may be referred to and claimed individually or in
any combination with other members of the group or other elements
found herein. It is anticipated that one or more members of a group
may be included in, or deleted from, a group for reasons of
convenience and/or patentability. When any such inclusion or
deletion occurs, the specification is deemed to contain the group
as modified thus fulfilling the written description of all Markush
groups used in the appended claims.
[0111] Certain embodiments of this invention are described herein,
including the best mode known to the inventors for carrying out the
invention. Of course, variations on these described embodiments
will become apparent to those of ordinary skill in the art upon
reading the foregoing description. The inventor expects skilled
artisans to employ such variations as appropriate, and the
inventors intend for the invention to be practiced otherwise than
specifically described herein. Accordingly, this invention includes
all modifications and equivalents of the subject matter recited in
the claims appended hereto as permitted by applicable law.
Moreover, any combination of the above-described elements in all
possible variations thereof is encompassed by the invention unless
otherwise indicated herein or otherwise clearly contradicted by
context.
[0112] In closing, it is to be understood that the embodiments of
the invention disclosed herein are illustrative of the principles
of the present invention. Other modifications that may be employed
are within the scope of the invention. Thus, by way of example, but
not of limitation, alternative configurations of the present
invention may be utilized in accordance with the teachings herein.
Accordingly, the present invention is not limited to that precisely
as shown and described.
* * * * *